Using commit hashes to make release packaging more robust

DrupalorgProjectPackageRelease.class.php uses fileFindYoungest() to help determine if a release should be packaged. Instead, it should compare the commit hash against the commit hash at the last packaging. First, we will need a field to store what the last-packaged commit hash is.

This will allow us to package dev releases without the 300 second check, sometimes preventing close-together commits from being considered for packaging. And improve the handling of files dated in the future.

Production outage: No
Change affects: Drupal.org Packaging
Deployment schedule: Week of 2016-06-27
Backout plan: Revert or fix in place